灰铸铁缸套内表面Nd∶YAG激光NiTi合金化研究

Laser suface alloying of cylinder bore gray cast iron with Ni-Ti by Nd∶YAG laser

采用预置涂层法对灰铸铁缸套内表面进行Nd∶YAG激光Ni Ti合金化研究 ,可得到表面平整的激光合金化层。该材质的灰铸铁存在较大的裂纹倾向 ,在适当的涂层厚度、工艺参数和预热条件下 ,可获得无裂纹合金化区。激光强化层包括合金化区和淬火马氏体区和二者之间很窄的过热区 ,其硬度较铸铁基体显著提高 ;微观组织以亚共晶介稳组织为主。

Nd∶YAG laser alloying Ni Ti with pre placed coating on specific cylinder bore gray cast iron was investigated and smooth surface alloyed layers were available.This kind of laser alloying cast iron was quite sensitive to cracking.Crack free alloyed layers were possible with appropriate coating thickness,alloying parameters and preheating.The alloyed layer consists of alloyed zone,remelting zone and quenching zone,whose micro hardness is increased dramatically.The main microstructure of the alloyed layer is the hypoeutectic sub stable structure.